In current large-scale networks, information flows through a series of nodes in the network from one location or site to another. As the network grows, more and more transmission lines may be added to handle the heavy traffic flow between nodes. Network switches are used to connect one transmission line to another and to manage information flow through a network. As networks increase in size and complexity, more switches and transmission lines are added. An example of such a network switch is the “MultiWave CoreDirector” switch, manufactured and distributed by CIENA Corporation of Linthicum, Md.
Switches in large networks often store link connectivity information about other switches. Such network topology information is often useful when a fault is detected. In particular, if a transmission line becomes defective, network topology information distributed among various switches in the network can be used to reroute data flow around the fault. Each switch then typically broadcasts to other switches in the network a new network topology. Such information is broadcast for each transmission line. In networks having many transmission lines and switches, however, distribution of topology information can be cumbersome and inefficient. For example, if multiple transmission lines connect the same switches, the same topology information may be unnecessarily duplicated for each transmission line. Accordingly, so-called aggregated links have been proposed in which multiple transmission lines interconnecting the same switches or network elements are treated as a single link. Thus, corresponding topology information of the aggregated links is shared among various switches in the network, as opposed to numerous copies of the same information for individual lines within the aggregated link. Aggregated links are discussed in greater detail in U.S. patent application Ser. No. 10/061,995 titled “Link Aggregation”, filed Feb. 1, 2002.
A particular channel is often used to carry topology information between two network elements or switches on a line within an aggregated link, if the line becomes faulty, however, the control channel maybe disrupted, thereby hindering adequate network monitoring.